Investigation Of The Immunologic Disorder Pathogenesis Of Infant With Sepsis

ObjectiveTo investigate role of CD14⁺ monocyte HLA-DR expression,Cytokine,CD4⁺CD25⁺ Foxp3^highregulatory T cells and Th17 cells in aberrant immune response of infant with sepsis.Methods36 infants with sepsis and 16 age-matched healthy infants were studied.CD14⁺ monocyte HLA-DR expression and the proportion of CD4⁺CD25⁺ Foxp3^highregulatory T cells(Treg cells)were analyzed by flow cytometry.Real-time PCR were used to evaluate the mRNA levels of Foxp3,CTLA-4,GITR,IL-10 and IL-6 in CD4-positive cells.Cytokine(IL-1β,IL-6,TNF-α,IL-10 and TGF-β)were measured by Enzyme-Linked Immunosorbent Assay(ELISA).12 infants with sepsis and 10 age-matched healthy infants were studied.The proportion of Th17 cells was analyzed by flow cytometry.Real-time PeR were used to evaluate the mRNA levels of IL-17A,IL-17F,ROR-γt,IL-6,TGF-βand IL23p19 in CD4-positive cells.Concentrations of IL-17A,IL-6 and TGF-βin serum were measured by Enzyme-Linked Immunosorbent Assay(ELISA).Results(1)36 infants were divided into two groups according to HLA-DR expression＜or＞30%:DR-H group and DR-L group.Pediatric critical illness score in DR-H group was higher than that in DR-L group(P＜0.05).(2)Expression changes of cytokines in serum:concentrations of pro-inflammatory cytokine(such as IL-1β,IL-6,and TNF-αetc)in serum were significantly elevated in DR-H group and DR-L group(P＜0.05).There is no significant difference of IL-1βand IL-6 found between DR-H and DR-L group,while protein level of TNF-αin DR-H group was detected to be more higher than that in DR-L group(P＜0.05).Transcription level of IL-6 was significantly up-regulated in DR-H group and DR-L group(P＜0.05), and the mRNA level of IL-6 in the latter was found to be higher than that in the former. On the other hand,the protein level of ant-inflammatory cytokine(IL-10)was significantly raised in DR-H group and DR-L group(P＜0.05),the mRNA level of IL-10 was significantly raised in DR-L group(P＜0.05),while mRNA and protein levels of IL-10 in DR-L group were higher than those in DR-H group(P＜0.05).The protein concentration of TGF-βin serum was significantly decreased in DR-H group and DR-L group compared with healthy control group(P＜0.05).(3)The proportion of CD4⁺CD25⁺ Foxp3^highregulatory T cells in peripheral blood in DR-L group was found to be significantly higher than that in healthy control or DR-H group(P＜0.05).Compared with healthy control group,the mRNA levels of Foxp3,CTLA-4,IL-10 were significantly increased in DR-L group(P＜0.05),while transcription levlels of four genes associated with CD4⁺CD25⁺ Treg(Foxp3,CTLA-4, IL-10 and GITR)in DR-L group were detected to be higher than those in DR-H group (P＜0.05).(4)The proportion of Th17 in peripheral blood from sepsis patients was found to be higher than that in healthy control.Consistent with the result above,transcription and proteins levels of IL-17 were significantly increased in sepsis group(P＜0.05). Expression levels of the transcription factors associated with difference of Th17 cells (such as ROR-γt and IL-6)were significantly raised in sepsis group(P＜0.05).Protein level of IL-6 in serum was significantly higher in sepsis group(P＜0.05).No differences of IL-23p19 mRNA level was found between patients with sepsis and healthy control (P＞0.05).Conclusions (1)HLA-DR expression on monocytes cells could be a valuable index to judge the critical level of pediatric illness and serve as an index to predict outcome of infant with sepsis.(2)Over-expression of pro-inflammatory cytokine was found along with all the phage of sepsis.Aberrant increase levels of IL-10 and CD4⁺CD25⁺ Foxp3^highregulatory T cells may be contributed to the pathogenic mechanism of immune suppression.(3)Over-activation of Th17 cells may be one of the factors causing aberrant increase of pro-inflammatory cytokine in infant with sepsis.